Sky News has learnt that participants in a call with the prime minister were informed that he would no longer attend the talks scheduled for Monday afternoon.

The discussion with companies including Pensionbee and Oxford Nanopore, both of which floated in London last year, had been convened to assess the City's attractiveness as a listing venue for high-growth businesses.

One source said the call would still go ahead, and would instead be chaired by the digital minister Chris Philip and City minister John Glen.

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Mr Johnson is expected to respond to the senior civil servant Sue Gray's report in the House of Commons on Monday afternoon - a day that could determine the fate of his premiership.

Among the others expected to be present on the call are CMR Surgical, a manufacturer of advanced surgical robotics; Oaknorth, the digital bank; Clearscore, a credit scoring provider; and Checkout.com, which recently became one of the most valuable private companies in British history when it raised new funding at a $40bn valuation.

Sky News reported last week that Lord Hill, the former EU commissioner, and Ron Kalifa, the former Worldpay chief, were also expected to join the meeting.

Both Lord Hill and Mr Kalifa have overseen key reviews for the Treasury in the last 12 months aimed at strengthening the UK's position as a hub for listings for high-growth businesses and as a global centre for the fintech sector.

Some tech founders and investors have expressed anxiety about London's efforts to project itself as a natural home for such businesses to go public following the travails of companies such as THG, the online health and beauty retailer and logistics group.

Mr Johnson hosted a similar meeting in December 2020, which was attended by bosses from Darktrace, Deliveroo, Trustpilot and Wise - all of which subsequently floated on the London market.

The quartet have had mixed fortunes since, with Deliveroo in particular enduring a bumpy start to life as a quoted company.

None of those contacted by Sky News would comment on their attendance at the meeting.